Anthony Atala — Peruvian Scientist

Anthony Atala, M.D. is the W.H. Boyce Professor and Director of the Wake Forest Institute for Regenerative Medicine, and Chair of the Department of Urology at Wake Forest School of Medicine in North Carolina. Regenerative medicine is "a practice that aims to refurbish diseased or damaged tissue using the body's own healthy cells.".. (wikipedia)

Building a solid organ like the liver in the lab is different and harder than with an organ like the bladder because solid organs are very vascular.
When a patient does get an organ from another person, it comes from a different body. It has different properties, and a person's natural tendency is to reject that organ.